Flystrike, Wound Management, and Vector Control
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What do flystrike, wound management, and vector control all have in common? Knowing about each one can save your goats.
– By Dr. Erin Masur DVM It’s my least favorite phone call of the year. After that first call about maggots, all you’ll see for the next month are maggots, maggots, and more maggots. “Doc, I didn’t even realize there was a wound there. But now that I’ve got her caught and I’m really looking at it, there’s something crawling around in there. I think you better come out.” Well, it’s not one something. It’s a thousand somethings.
Reasons to Keep Vectors Under Control
There are many good reasons to have a multimodal vector control plan on your farm before the summer starts. Vector control refers to mitigating airborne pests like flies, midges, and mosquitos. Multimodal vector control is when different strategies are combined and used concurrently for maximum efficacy. Here in New England, I urge my clients to start implementing their vector control measures by April and keep them active until November.
As a farm veterinarian and a farmer myself, I believe the most important reason is to relieve goats of the stress and distraction these flying pests impose. In the veterinary field, we have long understood how fly pressure triggers a stress response in livestock. Flies keep our goats from doing what they ought to be doing — eating, socializing, rearing their young, and resting. Not only does this cause unhappy goats, but it will impact commodities such as milk and meat. For those of us relying on agritourism as part of our business plans, it also affects the experiences our visitors have. They will be preoccupied waving off flies and quick to notice the one goat hanging out by herself, stomping her legs.
Flystrike from Wounds
Another reasons to keep vectors under control is to reduce the possibility of flystrike. While some wounds are planned (such as disbudding and banding), many are accidents — especially with goats! While maggots (the larvae of the blowfly) are most often associated with wounds, they can also be a consequence of diarrhea-caked rear ends, weepy eyes, foot rot, or swollen postpartum vulvas. Any exposed, raw, swollen, or moist tissues are vulnerable to fly strike. A single adult fly is attracted to decomposing tissues within minutes and can lay up to 300 eggs at a time. Depending on the conditions, these eggs hatch as larvae within 8 to 24 hours. That means a very rapid and potentially fatal cycle is underway once blowflies find a favorable environment.
Freshly hatched maggots are precocious, moving rapidly to consume flesh. They burrow deeper, passing through the superficial layers of the skin, moving steadily and doggedly into more central and vital locations. As they thrive, adult flies at the surface continuously lay more eggs. At first, affected animals may simply seem irritated and distracted. In a matter of hours, they may self-isolate, stop eating, and become depressed. As the maggots consume tissue, they release enzymes to expedite tissue decay, and damaged tissues release toxins as secondary infection sets in. In as little as half a day, fly strike becomes life-threatening.
How Does Vector Control Affect Biosecurity?
Another important reason to control flying vectors on your farm is to uphold prudent biosecurity and reduce the risk of disease transmission these pests may import from your neighboring farms. Face flies can transmit pinkeye throughout a herd, biting midges can spread Bluetongue Virus up to a mile away, and mosquitoes can transmit Cache Valley Virus up to three miles away.
Controlling Vectors to Prevent Flystrike
How can a farmer control airborne vectors to relieve their goats of fly pressure, prevent flystrike, and protect their herd from infectious diseases? Whether you’re certified organic and strict — or not shy about insecticide use — plenty of options will work for your farm’s philosophy and budget. The different categories of vector control are property hygiene, trapping and deterrence, sprays and topicals, and herd health program planning. Combining strategies from each category creates a multimodal vector control program for the best possible control.
Simple property maintenance, such as prompt manure disposal and the mitigation of standing water, shouldn’t be forgotten as part of your vector management plan. Pasture rotation goes hand in hand with these strategies, ensuring soil erosion and pasture wear are minimized over the long term. Hanging bag-style traps that attract flies and trap them inside the bag is very effective if used correctly and maintained. On my farm, one trap hangs per every acre, and they are changed as soon as they are full. Large box-style traps can be installed on pasture, mimicking the silhouette of a large animal and drawing in flies and retaining them. Use box fans, air movers, or fly vacuums to encourage brisk air flow inside your barns and buildings. Amplify the breeze running through your smaller shelter structures by rotating them to catch the right angle of wind direction. Creating air flow provides a mechanical obstacle to flying vectors and keeps the floors and the ground dry.
Look at your health program to see how you can fine-tune your timing. Plan it so disbudding sites and banding sites are fully healed before vector season. In the northeast, most producers avoid elective procedures during the summer months; however, don’t assume you’re in the clear by September. That’s when most of the maggot calls start rolling in. Blow flies reach peak reproduction in the Northeast in September, which incidentally is the start of rutting season. This, of course, is when goats seem more prone to accidents and wounding themselves. Planning ahead is also a good time to look into fly predators. Fly predators are exactly what they sound like and are an effective, holistic way to prevent flies from beginning to propagate on your farm. They need several weeks to hatch and must be ordered well in advance.
What Else can be Done to Prevent Flystrike
After you think about your property, the environment, and your health program, consider what you may want to do to protect the animals. Don’t underestimate a good fly spray. Regularly applying a spray of your choosing during the height of fly pressure goes a long way, especially if you focus on the belly and the groin. For face flies, apply a fly ointment carefully so as not to run into the eyes. Use ointments around the immediate perimeter of open wounds, as long as it’s intact skin. The only product that’s safe to apply directly to an open wound or vulnerable tissues is Catron IV. This aerosol spray has a dedicated place on my truck to be used for any wound assessment, any emergency surgery that can’t be planned, to drive away maggots, and to hand out to farmers to keep on hand.
Lastly, convenient feed-through options are gaining traction, including traditional larvicides or the more holistic granulated garlic. If you’re interested in garlic, make sure to read the literature available. Garlic is currently widely debated, so some researchers find it to be successful, and others are not. Correct dosing is pivotal — alliums at too high of a dose can be harmful. Consult a nutritionist or a livestock veterinarian who knows your herd and the current literature before implementing garlic.
Accidents happen, and farm life often doesn’t go according to plan, but just like every other facet of good animal husbandry, you can put your best foot forward by being prepared and having options. As a farm vet, it’s my job to be there for my clients when accidents happen. However, nothing makes me feel more successful than discovering that I helped my clients be so prepared that we completely prevented a problem like flystrike.
Dr. Erin Masur is a livestock veterinarian located in the northeast with a passion for small ruminant parasitology. On her own farm, she raises sheep, ducks, and children. You can keep up with her research at earlybirdworm.com, or check out her services at sheeprockvet.com. For more frequent updates, you can find her on social media by searching for Sheep Rock Vet or Fork You Farms.
Originally published in the September/October 2023 issue of Goat Journal and regularly vetted for accuracy.
